1. Field of the Invention
The present invention generally relates to a semiconductor device and a method of forming the same. More specifically, the present invention relates to a semiconductor device with gate-overlap capacitance and a method of forming the same.
Priority is claimed on Japanese Patent Application No. 2007-247219 filed Sep. 25, 2007, the content of which is incorporated herein by reference.
2. Description of the Related Art
In recent years, there has been progressed high density integration and shrinkage of a semiconductor device with various techniques.
Japanese Unexamined Patent Application, First Publication, No. 9-8290 discloses a vertical MOS transistor that includes a semiconductor pillar that extends vertically from a main surface of a semiconductor substrate. The pillar is covered by a gate insulating film. A gate electrode is provided on the gate insulating film so that the gate electrode is separated by the gate insulating film from the gate electrode.
Japanese Unexamined Patent Application, First Publication, No. 9-8295 discloses a semiconductor device that includes a semiconductor pillar extending from a semiconductor substrate. A drain is selectively formed in a portion of the semiconductor pillar. A source is formed on the surface of the semiconductor substrate. A gate insulating film extends along the side surface of the pillar. A gate electrode is provided on the gate insulating film so that the gate electrode surrounds the pillar. A photon-shielding material is provided which covers the gate electrode.
Japanese Unexamined Patent Application, First Publication, No. 2004-221242 discloses a semiconductor integrated circuit including a vertical MISFET that includes a multi-layered pillar structure having upper and lower semiconductor layers. An insulating film extends along the side surface of multi-layered pillar structure. A conductive film extends along the insulating film so that the conductive film and the insulating film surround the side surface of multi-layered pillar structure.